Current mm interferometers Sébastien Muller Nordic ARC Onsala Space Observatory Sweden Turku Summer School – June 2009

Current mm interferometers: few facts - Mm interferometry = Young technique PdBI: early 90s SMA dedication: 2003

Design started in 1979 First antenna completed in antennas interferometer observations opened for guest observers 1990 First fringes at 230 GHz antennas configuration antennas configuration2002 New generation receivers2007 & extension of the tracks 350 GHz receivers2009… Broad-band correlator PdBI milestones

1984The SMA project (6-elements array) was proposed by the SAO. 1996The ASIAA joined the project, starting SMART (Submillimeter Array of Taiwan) project. 1999First two SAO antennas were completed at MK and the first fringe was obtained. 2001First image was obtained with 3 antennas. 2001First ASIAA antenna was assembled at MK nd ASIAA antenna was assembled at MK. 2003The SMA (eight elements) was dedicated Regular science operations SMA milestones

Current mm interferometers: few facts - Mm interferometry = Young technique PdBI: early 90s SMA dedication: Few mm interferometers, mostly in the Northern hemisphere

Current mm interferometers: few facts - Mm interferometry = Young technique PdBI: early 90s SMA dedication: Few mm interferometers, mostly in the Northern hemisphere - Small array N ant < 15 limited instantaneous uv-coverage -> super-synthesis - Limited total collecting area - High altitude site for dry and stable atmosphere

Altitude = 2550m N ant = 6 D = 15m Area = 1060 m 2 Altitude = 2200m N ant = 15 D = 6/10m Area = 772 m 2 Altitude = 1340m N ant = 6 D = 10m Area = 471 m 2 Altitude = 4080m N ant = 8 D = 6m Area = 226 m 2 Altitude = 5060m N ant = 50 D = 12m Area = 5652 m 2

(Demonstration of the technique) High spectral resolution Polarization capability Bandwidth of up to 4 GHz Angular resolution up to ~0.3 arcsec Detection of molecules up to z=6.42 Open the appetite of (radio-mm) astronomers ! -> ALMA What did the current generation of mm interferometers achieve ?

Let’s take two examples in more details: Plateau de Bure interferometer & SubMillimeter Array

SMA

Frequency coverage PdBI SMA 80 – 116 GHz 129 – 174 GHz 201 – 267 GHz186 – 242 GHz 277 – 371 GHz272 – 349 GHz 320 – 420 GHz (7 ant, high Tsys) 635 – 690 GHz 1 band at a timeDual frequency operations possible (L/H) + 22 GHz water vapor radiometer

FWHM primary beam Freq. (GHz) SMAPdBI ’’ 23052’’21’’ 34535’’14’’ 69017’’- -> Mosaicing for extended sources

Configurations / Angular resolution GHz D: 5’’ deep integration CD: 3.5’’ mosaicing BC: 1.7’’ HRA mapping B: 1.2’’ AB: 1’’ A: 0.8’’ very compact sources Bmax = 760 m GHz Subcompact: 5’’ extended sources Compact: 2.5’’ Compact NS Southern sources Extended: 0.7’’ (Very extended) Bmax = 508 m Summer Winter

Very flexible: multiple lines with different spectral resolution (up to 25 kHz, on a limited bandwidth) SMA correlator 10 GHz LSB 2 GHz USB

13 CO(2-1) C 18 O(2-1 ) 12 CO(2-1) LSB NGC GHz IF x 2 = 10 GHz Phase Amplitude Phase Amplitude Simultaneous multiple lines / isotopes observations with the SMA USB

HOR pola VER pola Q1 Q2 Q3 Q4 Dual pola 4 GHz Simultaneous 2 GHz bandwidth Dual polarization capability 1 GHz bandwidth/unit(2 units possible at the moment) 8 independent spectral units can be allocated: with 20 to 320 MHz bandwidth with 2.5 MHz to 40 kHz channel spacing PdBI correlator A new broadband correlator (WIDEX) will be installed this year

Example of correlator setup: multi-line survey

Data reduction / Imaging PdBI GILDAS: CLIC -> MAPPING SMA MIR/IDL -> AIPS, MIRIAD, GILDAS

Tools for proposal preparation - GILDAS/ASTRO - IRAM webpages - SMA Observer Center -> Tools Beam/sensitivity calculator Calibrator list Passband visualizer

Proposals to PdBI Increasing pressure on observing time Courtesy R. Neri

Example values given for PdBI Courtesy R. Neri How to improve the sensitivity ?

Near future Early Science in 2011 More tomorrow ALMA/ESO

Future of mm interferometry ? Improve the sensitivity: - Large array - Better receivers - Broad bandwidth (continuum sensitivity, line survey) Improve the quality: - Real time phase monitoring (~adaptive optic) Limited fov: - On-the-fly mapping - Multi-beam (pixel) detectors Longer baselines Mm VLBI … another challenge

Evolution of PdBI -> NOEMA Northern Extended Millimeter Array - Double the number of antennas: 6 -> 12 - Broad bandwidth -> 32 GHz - Extend baselines: 0.8 -> 1.6 km And possible further evolution (better receivers, multi-beam …) NOEMA/IRAM

From NOEMA project/IRAM